Removal of naphthenic acids from hydrocarbon oils



Patented Sept. 15, 1931 UNITED STTES ATENT. OFFICE NORMAN E. LEMMON AND FRANK V. GRIMM, OF WHITING, INDIANA, ASSIG-NORS TO STANDARD OIL COMPANY, OF WHITING, INDIANA, CORPORATION OF INDIANA REMOVAL OF NAIPHTI-IENIG ACIDS FROM l-IYDROCARBON OILS No Drawing. Application filed May 14,

This invention relates to the removal of naphthenic acids from hydrocarbon oils and particularly relates to such oils which contain relatively small amounts of these acids, for example, of an acidity of less than 0.2 mg. of KOH, per gram of oil. Such oils may be of natural occurrence or may result from the extraction of a part of the acids.

It is found that if oils containing such acids are treated with strong sulfuric acid and contacted with Fullers earth, or similar clays, the naphthenic acids cannot be efiectively removed unless a prohibitive amount of clay is used.

We have found that if such oils are subjected to a mild treatment with sulfuric acid, the naphthenic acids are converted to a form which may be readily removed by contacting with clay. Care must be taken to avoid acid treatment of such severity that the clay is rendered ineffective in the removal of naphthenic acids.

As an example of a mild treatment, which we have found to be efiective for the 2,5 purposes of this invention, we may mention 0.1 pound of 89% sulfuric acid, per gallon of oil. For good results, the acid strength should not substantially exceed 89 Weaker acid may be employed, but in that case, somewhat larger amounts should be used. By way of example, it may be stated that up to 0.5 pound of to acid, per gallon of oil, is a suitable mild acid treatment within the terms of the present invention.

After the acid treatment, the oil is settled and as much of the sludge as is practicable is withdrawn. The sour oil is agitated with finely divided earth at a temperature of 150 to 300 F. The clay, with its adsorbed sludge and coloring matter, is separated by filtration, yielding a substantially neutral oil of-good color and color stability.

The following specific example is given for purposes of illustration.

A naphthenic lubricating distillate of an acidity corresponding to 0.12 mg. of KOH per gram of oil was treated wlth 0.1 pound of 89% of sulfuric acid, per gallon of oil, and was then treated with 5 pounds of clay per 100 50 pounds of oil, in the manner described above.

1928. Serial No. 277,789.

The final acidity of the oil was 0.045 mg. KOH, per gram of oil.

For the purpose of comparison, it may be stated that when the acid treatment of the present invention is omitted the final acida ity of'the above distillate is found to be 0.10, while if the same oil is found to be subjected to a severe acid treatment, for example, with 0.6 pound of 89% sulfuric acid per gallon of oil, the final acidityis 0.10.

lVhile the present invention has been de-' scribed in connection with the details of a specific example, it must be understood that such details are not intended to be limitative upon the scope of the invention, except in so 68 far as included in the accompanying claims.

We claim:

1. The method of substantially removing naphthenic acids from hydrocarbon oils of a naphthenic acidity of not more than about '10 0.2 mg. of KOH, per gram of oil, which consists in subjecting said oil to a sulphuric acid treatment equivalent in effect to treatment with 0.1 pound of 89% sulfuric acid, per gallon of oil, and thereafter treating the sour oil 16 with clay.

2. The method of substantially removing.

naphthenic acids from hydrocarbon oils of a naphthenic acidity of not more than about 0.2 mg. of KOH, per gram of oil, which cona. sists in subjecting said oil to a sulfuric acid treatment equivalent in effect to treatment with 0.1 pound of 89% sulfuric acid, per gallon of oil, and thereafter treating the sour oil with clay in the proportion of about 5 pounds 88 of clay to 100 pounds of oil.

3. The method of substantially removing naphthenic acids from hydrocarbon oils of a naphthenic acidity of not more than about 0.2 mg. of KOH, per gram of oil, which con- 90 sists in treating said oil with 0.1 pound of 89% sulfuric acid, per gallon of oil, and thereafter treating the sour oil with clay in the proportion of about 5 pounds of clay to 100 pounds of oil.

4. The method of substantially removing naphthenic acids from hydrocarbon oils of a naphthenic acidity of not more than about 0.2 mg. of KOH, per gram of oil, which consists in treating said oil with 0.1 pound of 89% sulfuric acid, per gallon of oil and thereafter treating the sour oil with clay in the proportion of about 5 pounds of clay to 100 pounds of oil at a temperature between 150 and 300 F.

5. The method of substantially removing naphthenic acids from hydrocarbon oils of a naphthenic acidity of not more than about 0.2 mg. of KOH, per gram of oil, which consists in treating said oil with sulfuric acid, having astrength not exceeding 89%, and equivalent in effect to treatment with 0.5 pound per gallon of oil of such acid having the strength of from eighty to eight-five per cent, and thereafter treating the sour oil with clay,

"6. The method of removing naphthenic acids, from hydrocarbon oils containing same in small quantity, which consists in subject- 9 ing said oils-to a mild sulfuric acid treatment suflicient to convert the naphthenic acids into a form readily removable by contact clay, said sulfuric acid treatment being equivalent in effect to treatment with 0.5 lb. per gallon of oil of sulfuric acid having a strength of from about 80 toabout 85%, and then subje'cting the said oil to treatment with clay, said sulfuric acid treatment being further characterized in that it is insufiicient to render the clay ineffective in the removal of the naphthenic acids.

7 The method of removing naphthenic acids from hydrocarbon oils of a naphthenic acidity of not more than about 0.2 mg. of KOH, per gram of oil, which consists in sub- Jecting said oils to a mild sulfuric acid treatment sufficient to convert the naphthenic acids into a form readily removable by contact clay, and then subjecting the said oil to treatment with clay, said sulfuric acid treatmentbeing further characterized in that it is insufficient to render the clay ineffective in the removal of the naphthenic acids.

In witness whereof, we have hereunto set N ourhands this-3rd day of May, 1928.

NORMAN E. LEMMON.

FRANK V. GRIMM. 

